This view of the twilight sky and Martian horizon taken by NASA's Curiosity Mars rover includes Earth as the brightest point of light in the night sky. Earth is a little left of center in the image, and our moon is just below Earth.

This frame from an animation from NASA's Mars rover Curiosity shows the rover drilling into rock target 'Cumberland.' The drilling was performed during the 279th Martian day, or sol, of the Curiosity's work on Mars (May 19, 2013).

This image from the Mars Hand Lens Imager on NASA's Mars rover Curiosity shows the patch of rock cleaned by the first use of the rover's Dust Removal Tool (DRT). The tool is a motorized, wire-bristle brush on the turret at the end of the rover's arm.

The two bodies in this portion of an evening-sky view by NASA's Mars rover Curiosity are Earth and Earth's moon. The rover's Mast Camera (Mastcam) imaged them in the twilight sky of Curiosity's 529th Martian day, or sol (Jan. 31, 2014).

This pairing illustrates the first time that NASA's Mars rover Curiosity collected a scoop of soil on Mars. At right, the ground location 'Rocknest,' at left, after the scoop of sand and dust had been removed.

This image from NASA's Curiosity shows a scoop full of sand and dust lifted by the rover's first use of the scoop on its robotic arm. In the foreground, near bottom of this image, the bright object visible on the ground might be a piece of rover hardware.

This image from a video shows the first Martian material collected by the scoop on the robotic arm of NASA's Mars rover Curiosity. The material vibrated inside the scoop after it was lifted from the ground.

This cutaway view shows the internal chambers of the Collection and Handling for In-Situ Martian Rock Analysis (CHIMRA) device, attached to the turret at the end of the robotic arm on NASA's Curiosity Mars rover.

This false-color engineering drawing shows the Collection and Handling for In-Situ Martian Rock Analysis (CHIMRA) device, attached to the turret at the end of the robotic arm on NASA's Curiosity Mars rover.

NASA's Mars rover Curiosity cut a wheel scuff mark into a wind-formed ripple at the 'Rocknest' site to give researchers a better opportunity to examine the particle-size distribution of the material forming the ripple.

This patch of windblown sand and dust downhill from a cluster of dark rocks is the 'Rocknest' site, which has been selected as the likely location for first use of the scoop on the arm of NASA's Mars rover Curiosity.

This image shows a test using an engineering model of the soil scoop for NASA's Mars rover Curiosity. The scoop dips to about 1.4 inches (3.5 centimeters) deep. This test took place at NASA's Jet Propulsion Laboratory, Pasadena , Calif., in 2011.

This stereo image from the Mast Camera (Mastcam) on NASA's Mars rover Curiosity shows a rock outcrop called 'Hottah,' cited as evidence for vigorous flow of water in a long-ago Martian stream. You need 3D glasses to view this image.

This is the highest-resolution view that the MAHLI camera on NASA's Mars rover Curiosity acquired of the top of a rock called 'Bathurst Inlet'; the rock is dark gray and is so fine-grained that MAHLI cannot resolve grains or crystals in it.

This set of images compares the 'Link' outcrop of rocks on Mars (left) with similar rocks seen on Earth (right). The 'Link' outcrop shows rounded gravel fragments, or clasts, up to a couple inches (few centimeters), within the rock outcrop.

This false-color map shows the area within Gale Crater on Mars, where NASA's Curiosity rover landed on Aug. 5, 2012 PDT (Aug. 6, 2012 EDT). The rover is heading toward Glenelg, just to the lower right of Bradbury.

This image shows the topography, with shading added, around the area where NASA's Curiosity rover landed. An alluvial fan, or fan-shaped deposit where debris spreads out downslope, has been highlighted in lighter colors for better viewing.

NASA's Curiosity rover found evidence for an ancient, flowing stream on Mars at a few sites, including the rock outcrop pictured here, which the science team has named 'Hottah' after Hottah Lake in Canada's Northwest Territories.

This image shows the robotic arm of NASA's Mars rover Curiosity with the first rock touched by an instrument on the arm. The rover placed the APXS instrument onto the rock to assess what chemical elements were present in the rock.